The present invention relates generally to an optical component suitable for use in glazing, and in particular in glazing openings in fixed structures such as commercial, industrial or domestic buildings. The present invention will hereinafter be described with specific reference to its application to such fixed structures without prejudice to the generality of the invention, however, which may nevertheless be used in other applications where its characteristic optical features may be found to be of utility. In particular, this may include, without limitation, glazing for openings in vehicles, or for covering the exit opening of light sources or light transmission devices.
It is known that the intensity of illumination provided by daylight increases generally with higher angles of elevation of incident light. This may be influenced on clear days by direct sunlight, in which case the peak intensity may lie at a lower angle in dependence on the elevation of the sun. For this reason the illumination within a building by daylight entering through window or other openings is recognised to have greatest intensity closest to and immediately beneath the window opening, and to reduce in intensity with an increase in distance from the window. For the purposes of the present specification the term "window" will be understood to refer to any opening in a vertical or near-vertical (that is upright) wall or facade, whilst an opening in a horizontal or inclined surface will be termed a roof light.
For most commercial buildings where the occupants are expected to be working on horizontal surfaces such as desks or tables, it has become conventional for the majority, if not all of the external surfaces to be formed as glazed window openings apart from any essential structural components required to support the glazing. Buildings having a depth greater than that which can be illuminated even from totally glazed outside walls require permanent artificial lighting. This, however, constitutes a considerable consumption of energy, and it has been established that the energy consumption within large office blocks for illumination is in general greater than the energy consumption for heating in winter and/or cooling in summer.
The problem of glare is also encountered in such buildings, and this is generally approached by use of physical barriers such as blinds, whilst excess thermal input is approached by the use of optical coatings and/or air conditioning both of which can be adjusted to suit the immediate environmental conditions.
The present invention seeks to address the above problems by providing an optical component suitable for use as part of, or in association with, a glazing panel across an opening in a structure which will act to direct incident light into the building in such a way that it is more uniformly distributed through the interior.
Known so-called "daylighting" systems for improving the interior illumination through glazed windows act to divert incident light at high elevations by reflection at silvered surfaces so that the light is directed into the interior of the building at a higher angle of elevation than it would if transmitted through a conventional window pane where, by falling on a horizontal surface close to the window (which typically would not have a high degree of reflectivity), it is absorbed and therefore not available for use. One known such system also includes pivoted reflectors capable of being orientated such as to divert direct sunlight away from the building in order to reduce glare. Known such systems have the significant disadvantage that the reflecting surfaces act as a barrier to direct viewing through the windows and, therefore, although the distribution of daylight within the interior is improved the improvement is obtained only at the expense of a loss or reduction in visibility through the windows.
The present invention seeks to provide an optical component which, when used to enhance the illumination by daylight within a building interior, nevertheless allows those inside the building to obtain an almost normal, undistorted view through the window.